Purpose: Melanomas are vascular tumors with a high incidence of BRAF mutations driving tumor proliferation. Complete inhibition of vascular endothelial growth factor (VEGF) signaling has potential for enhanced antitumor efficacy.
Methods: Patients with advanced melanoma and adequate organ function were eligible. Sorafenib was given orally at 200 mg BiD for 5 days every week; bevacizumab was administered 5 mg/kg intravenously every 14 days. The primary objective was to determine clinical biological activity. The secondary objectives were safety, tolerability, and time to progression (TTP). Pharmacodynamic analysis included serum VEGF and soluble VEGF receptor-1 and VEGF receptor-2 performed at baseline, C1D15 and C2D1. The study was terminated during the first stage of a Simon two-stage design, after 14 of planned 21 subjects were enrolled.
Results: Of the 14 patients who received treatment, no objective tumor responses were observed. Stable disease (SD) ≥16 weeks was observed in 57 % patients, including three patients with SD lasting ≥1 year. Median TTP was 32 weeks. The most frequently reported drug-related adverse events (AEs) were hand-foot syndrome (57.1 %), fatigue (57.1 %), hypertension (64.3 %), and proteinuria (35.7). Grade 3/4 drug-related AEs were hypertension (14.2 %), hand-foot syndrome, proteinuria, and thrombocytopenia (7 % each). Patients with low VEGF (<300 pg/ml) experienced longer TTP than those with high VEGF [median 50 vs. 15 weeks, p = 0.02). A similar pattern was seen for VEGFR1 and VEGFR2, although it did not reach statistical significance.
Conclusions: Combined VEGF/VEGFR blockade using bevacizumab with sorafenib shows clinical activity. The linkage between VEGF levels and time to tumor progression needs further exploration.
Trial registration: ClinicalTrials.gov NCT00387751.